Gauges stop working and ASD light comes on when hot

[nzmonkie]

Been reading stuff here for a long time, but first post. I have an 03 TJ Sahara (Renegade), New Zealand export, as I'm in NZ. It is a 4.0L, 5 speed and is right hand drive.

So here is my problem. The last couple of weeks we have had some hot days, (summer here, sorry) and when it gets over about 80 F and I'm in traffic, the gauges stop working, My check engine light comes on and my ASD light comes on, also my low fuel light. The jeep keeps running though. If I stop and shut it off, it will start and run for several seconds, then the same lights come on and it shuts off, like the ASD is killing it. If I let it cool down, it will start and run fine. Usually just open the hood and the lid to the relay box for a few minutes. If the gauges come back on, it'll start.

I have checked for codes when the gauges stop and the lights are on, but I don't get any. It seems to happen when the thermometer in the mirror gets up to 34 C / 93.2 F. The gauges come back on around 31 C / 87.8 F when I get out of traffic and get air flow through the engine bay.. The outside air temp is around 29 C / 84.2 F. Below around 25 C / 77 F, I have no issues at all. Seems to be related to engine bay temps. Jeep is not overheating and stays at 195 F when driving at town speeds and about 212 F stopped in traffic, but doesn't go higher.

The only thing I have done recently is put grill inserts in. I can hear the fan (mechanical) running when I take off from a light. Not sure if the fan clutch is going out, but feels fine, or if the ASD relay is going out. I need to swap it with another one and wait for another hot day to try it.

Anyone else have this heat related issue, or any input would be appreciated. Or, am I looking in the completely wrong place. Thanks in advance, and thanks for reading all that. Wanted to give as much info as possible.

 

[macleanflood]

Run an instrument cluster self test.

Clean your battery terminals, make sure you've got a good battery and check all your grounds...firewall ground and behind both speaker covers and both kick panels.

Factory Service Manuals and the wiring diagrams are available free in the resources section.

-Mac

 

[nzmonkie]

Thanks, macleanflood. Battery terminals are pristine and tight. First thing I checked the first time it happened. Battery should be fine. No issues starting normally and cranks over quick, even when it won't stay running. I'll do the cluster self test tomorrow when it's cooler. I'll check grounds, but I don't think they're the problem. No issues with bumps and banging the dash doesn't have any effect. Engine bay temp is the only thing that seems to trigger it. Opening the hood and letting it cool off is the only way to get it to stay running shortly after it happens if I have shut it off. Or letting it sit long enough to cool down, like an hour or so.

 

[hear]

There's an ASD light??

 

[nzmonkie]

@hear, It's the SKIM light, my bad. I've got ASD stuck in my head from all the research.

 

[nzmonkie]

I have done the cluster self test. All good there, everything works as should. I had a look at the grounds and nothing obvious yet, no loose connections or corrosion. I know that doesn't mean they are good, but I don't want to do too much at once. I want to know for sure I found the problem. I switched the horn relay with the ASD relay. Now I just have to wait for another hot day to test it. Monday might fit the bill if the forecast holds. If that isn't it, then I'll clean all the grounds and go from there. Easiest things first.

 

[hear]

Does the horn still work? If there is no change in horn operation then its unlikely that relay was the culprit. IJS.

 

[nzmonkie]

As stated, everything works fine until it's over 80 f outside and the engine bay temps get high. Next day forecast for that is Monday here, so I'll have to wait until then to test it out. But that is the plan to test the relay, or eliminate it.

 

[CharlesHS]

As a test.... remove the grill inserts and drive the Jeep for a while to see if the problem remains or goes away.
From your explanation; the problem is temperature related.
Locate the ECM (firewall), disconnect the (3) 32 pin wiring harness connectors, inspect the harness connector and ECM receptacle for signs of oxidation or overheating. IF is oxidation found; disconnect the battery and clean with plastic safe electronics contact cleaner (DeoxIT D5) and allow to evaporate before reconnecting the battery.
Trace the ECM wiring harnesses along the firewall around the valve cover and threaded head stud (right rear corner of head); thoroughly inspect the plastic wire loom and wiring insulation for damage. The threaded head stud has been known to rub thru the wire loom and wiring insulation causing interruptions in the communications between the ECM, sensors, and instrument cluster (known problem).

 

[ColoJeep]

The only thing I have done recently is put grill inserts in. I can hear the fan (mechanical) running when I take off from a light.

You may have answered your own question. If it was working before installing the inserts , the inserts are restricting the airflow and driving up the underhood temps. Hopefully it's an easy fix.

 

[nzmonkie]

Thanks for all the suggestions. I'll trace some wires this weekend to eliminate some potential problems.

I installed the grill inserts over winter and it has only just started getting hot, so something could have failed in that time. But as always, look at what you just did. I did a fair amount of research and I didn't see anyone say that grill inserts negatively effected the temps. Maybe they are showing something else that is failing. They are a pain to pull out, as they are double side taped in and holding my front camera. So, removing them may be a last resort.

I've been in as high of temps and in start and stop traffic before with no issue. I know lot of people have jeeps in much higher temps than I'm having issues with, so I think it is more than the grill inserts. I did a fan clutch just over a year ago because it was running all the time and the heater didn't get very hot. It could be a bad fan clutch, as I got a cheap one. I only have issues in city traffic, or stop and go over 80 F. Once I'm on the open road or it is cooler than 80, all is good. My Jeep is black and the sun here is intense, so that doesn't help under hood temps either.

I should get a chance to test the relay swap on Monday, as it is going to be hot again then. I'll keep everyone posted and let you know what it is when I figure it out.

 

[hear]

I've seen mention of this before, but I'm pretty skeptical overall. I mean, my winch covers up a significant portion of my grill and it hasn't changed my running temp in the least. Now my trans temp definitely runs hotter in the summer when I'm heading due west. That late afternoon TX sun can be brutal, and it beating on my trans cooler, which is in front of my radiator, must be taking on heat. What's interesting is that my engine temp doesn't seem to be similarly affected. But the engine runs 40* warmer than the trans..... I have a degree in physics but I dropped thermo, so your guess is as good as mine.

 

[ColoJeep]

I only have issues in city traffic, or stop and go over 80 F. Once I'm on the open road or it is cooler than 80, all is good.

If the fan is locking up enough to hear it well , that shows it is working Okay typically. This all sounds like low airflow , Take the grille restrictions out .

 

[JeepDrivesBest]

Sounds like the PCM (ECM) is heat soaking and going into protection mode - I'd check that wiring around the valve cover area like mentioned above since heat expansion could be making an intermittent short worse.

 

[nzmonkie]

After running it on a hot day with my OBDII connected, it is overheating at idle. So, the gauges dying are a symptom. Weird that happens though. Not sure if I also have a crank or cam shaft sensor that doesn't like the heat. Jeep runs fine even when over heating though.

So, now onto the coolant system. Fan clutch passes the spin tests. Thermostat isn't that old, but may need to be changed. Will flush the radiator and see if that helps. Guessing it is an original radiator, so it is probably due.

Plenty of people run grill inserts in places over 100 F and have no issue. So, if they are causing the problem at 80 F, then there is something else wrong. I'd rather fix the actual problem then pull the inserts and have it overheat when I'm out in the middle of no where. So it's cooling system refresh time.

I'll keep this up to date. Nothing worse than an unresolved problem on a forum.

Thanks for all the advice and input.

 

[nzmonkie]

Small update. As stated earlier, I'm going item by item as I want to know exactly what the issue is instead of doing it all at once and having no idea.

So in that vein, I replaced the radiator cap today. It was warm out, but on the edge of when it would overheat in traffic before. It seems better and never got past 200 F idling and ran at about 188 F average while driving. No heavy traffic, and again with temps on the edge of when it would overheat before.

This leads to the problem that had me replace the thermostat and fan clutch originally, When I bought the jeep, it seemed to run cool and the heat didn't work very well. The thermostat didn't help, but I made sure it was a 91 C (195 F). That lead me to the fan clutch. It had failed locked and was always running, which kept the heat from working well when it was cold out. The fan clutch helped a lot, but it never felt like the heat worked as good as it should. I've never been roasted out, even with a half cab soft top at 33 F.

This could also be due to the bad radiator cap. The radiator would always be just below the fins when I checked it. I topped it up and it seems to be holding now. It is going to be cooler the next few days, 50's to 60's F for highs. That will let me check the heater. Gonna be a while till I can check the cooling. No warm weather in the forecast for a while. Typical South Island NZ. I've only had a couple of warm Christmas's here in 15 years. Don't believe them when they tell you they go to the beach, haha.

This info is mostly to keep track of the diagnosis and results for anyone chasing the same issues. Again, I'll keep this up to date until it is resolved and give a clear answer if possible. Not Sure I'll ever know why the gauges quit when it gets hot though.

Sorry, that ended up wordier than it should have been.

 

[nzmonkie]

It was hot again today, so got to test the radiator cap. Definite improvement. The jeep did not overheat idling, but the temp did continue to climb and not level off. It got to 93 C. The IAT got to 73 C and the mirror read 31 C. It was about 27 C outside air temp. The gauges cut out at 74 C IAT/31 C on the mirror, but the coolant temp was 93 C. So still have the gauge issue, but engine isn't overheating and boiling the coolant.

I will swap the thermostat next. If anything the engine seems to run on the cool side if the ambient temp isn't over 25 C. I also have a new fan clutch on the way. Better one than I put in 2 years ago that was stuck on. Parts are a pain to get here in NZ and not cheap. A fan clutch is more than you would spend on everything in the US.

Will report back after the thermostat. I am moving in the right direction. Just wish I could figure out what is causing the gauges to cut out. It is definitely heat related.

 

[nzmonkie]

I know it's been a while,but I said I would post the answer when I found it. It finally got hot enough to test again today. Letting it idle in the heat, it no longer over heats and the coolant never got above 95 C/ 203 F. So the radiator cap solved that issue.

The gauges still stopped working around 80 C/176 F IAT and 34 C/93 F on the mirror temp. The outside air temp was 27 C/80 F. I will get a heat gun and try heating up the IAT sensor, the grounds, the relays, and anything else I can think of one by one to see if I can find the source of the gauges failing.

The grill inserts do effect the air flow around the temp sensor for the outside air temp that shows in the mirror. It will read a couple of degrees warmer when driving and climbs steadily when sitting idling in hot air temps. I'm guessing if your not moving, it creates a spot of no air flow at the bottom of the grill where the temp sensor is, and when moving the air in that area is not moving as much as without. Either way, they are not causing my jeep to over heat. It was the radiator cap.

Thanks for coming along on the ride. I hate gremlins, so lets hope I can find this one.